This invention relates to a brake shoe used for a bicycle brake and the like, and more particularly to a brake shoe used mainly in calliper brakes.
Generally, a brake shoe, such as used in calliper brakes, comprises a main body or brake block of a rectangular prism-like shape made of friction material and a holder carrying the brake block and having mounting means for mounting the brake shoe to a brake arm of the calliper brake. The holder comprises a rectangular bottom, a front wall rising upright at the front end lengthwise of the bottom, and a pair of side walls rising from both lateral sides of the bottom, but a rear wall is omitted, thus forming a box-like shape opening upwardly and rearwardly. The brake block is pressed into the holder from the rear side thereof toward the front wall, whereby the front wall and pair of side walls embrace and hold the brake block.
When this brake shoe is used in a calliper brake, the front wall of the holder mounted to the brake arm is placed ahead of the forward rotation of the bicycle wheel. As a result, when braking is applied to the forwardly rotating wheel, the brake block, which is subjected to the frictional force caused between the wheel rim and the same, tends to move forward, but the front wall arrests this movement to retain the brake block within the holder. On the other hand, when braking is applied to the wheel as it rotates backwardly, which may occur, for example, when braking is applied to the bicycle on an upward slope, the backwardly rotating wheel tries to move the brake block rearwardly of the holder, causing the brake block to gradually shift and drop out through the open rear side, resulting in no braking being applied to the bicycle.
In order to solve this problem, a holder has been proposed which has a front and rear wall, whereby the brake block is embraced by the side walls and both front and rear walls. To form a brake shoe with this holder, the brake block is first inserted into the surrounding walls at four sides of the holder and then the holder walls are bent inwardly to press the block. With this construction, it is impossible to remove only the brake block for replacement. In other words, although the provision of the rear wall prevents the drop-out of brake block, another problem occurs when replacement of the brake block is needed or desired. For this reason, conventional brake shoes usually use a holder having no rear wall to facilitate insertion and removal of the brake block only.
This invention has been designed to overcome the problem of a brake block dropping out of an associated holder while permitting its easy replacement. Accordingly, an object of the invention is to provide a brake shoe having a brake block which is easy pressed into a holder and retained therein against accidental drop-out, but which is easily replaced when worn.
This object is achieved by providing a holder having no rear wall with protuberances on at least one of the opposite side walls which are directed toward the front wall. The protuberances cut into the brake block pressed into the holder from the rear side thereof so that the brake block is prevented from dropping out and permits an easy replacement of the brake block. When the brake block is replaced, the worn block is broken for removal and a new block is pressed into the holder through the open rear side. A press plate may be provided along one of the side walls to press or release the brake block, thereby facilitating its insertion and removal.
These and other objects and novel features of the invention will be more apparent from the following description taken in conjunction with the accompanying drawings.